Medial unicompartmental knee replacement (UKR) is a joint-preserving surgical procedure for treating isolated medial compartment osteoarthritis of the knee. Unlike a total knee replacement, which replaces all three compartments of the knee joint, a UKR only replaces the damaged medial (inner) compartment.

UKR involves the resurfacing of the damaged medial femoral condyle and medial tibial plateau with metal and plastic implants, while preserving the intact lateral and patellofemoral compartments. This bone and cartilage-sparing approach helps to maintain more natural knee kinematics and proprioception compared to a total knee replacement.

UKR can be an effective option for patients with isolated medial compartment arthritis, minimally affected lateral and patellofemoral compartments, and intact ligamentous stability. Potential advantages include smaller incisions, faster recovery, better range of motion, and improved functional outcomes.

Unsuitable candidates, such as those with inflammatory arthritis, ligamentous instability, or significant deformity, may be at higher risk of complications and early failure.